Toy construction sets comprised of several different configurations of releasably connectable units are entertaining and may be instructional to the user. In the past such types of toy units have not had the feature of both toppling elements arranged in a series when connected and at the same time provide a high degree of versatility as to the assembled structures that can be formed. Dominoes placed upright and in a row and then toppled have been an attraction for all ages but no releasably connectable domino units or construction sets using dominoes are known to have been provided.
Examples of prior known toy units using a toppling effect are found in U.S. Pat. Nos. 2,289,690, 2,713,489, 3,621,601 and 4,138,797.